The present invention relates to apparatus for the production and processing of rod-like articles, and more particularly to improvements in control systems for groups of machines (hereinafter called production lines) which are designed to produce and to process rod-like articles of the type wherein a tubular wrapper surrounds a filler of tobacco and/or filter material. Still more particularly, the invention relates to improvements in control systems for the prime movers of one or more machines in groups of machines which are employed to produce plain cigarettes, filter cigarettes, plain or filter-tipped cigars, cigarillos and/or filter rods and filter rod sections.
Presently known prime movers for cigarette making machines normally employ motors which can drive the moving parts of such machines at several speeds. As a rule, the motor is operated at two speeds, namely, at a lower speed for starting the machine and for operating it during a certain interval of time, and at a higher or normal operating speed at which the machine can turn out as many as 4,000 cigarettes per minute. The operation at a lower speed is desirable when it becomes necessary to make certain adjustments while the machine is running. Many recent types of cigarette rod making machines employ a pole-changeable electeic motor wherein the speed of revolving field varies inversely with the number of poles. Thus, the larger the pole number, the lower is the rotor speed and vice versa. Conventional mechanical, electrical or hydraulic clutches are employed in an attempt to prevent abrupt acceleration and eventual damage to parts of the machine when the motor is started or during speed changing. Means for preventing abrupt acceleration are particularly desirable in modern machines wherein the rotary parts must be rapidly accelerated from zero speed to a very high speed. However, a commercially available clutch cannot always prevent the production of defective articles, especially during acceleration from zero speed to a lower speed, during acceleration from a lower speed to a normal operating speed, and/or during deceleration from operating speed or from lower speed. It was found that the cigarettes which are produced during acceleration of the prime mover are underweight and that the cigarettes which are produced during deceleration of the machine are often overweight. The production of heavier cigarettes can take place during deceleration from normal speed to a lower speed or during deceleration to zero speed. Furthermore, the web of cigarette paper which is used as a wrapper for a continuous tobacco filler rod in a cigarette rod making machine tends to tear in response to sudden acceleration of the machine, and such tearing invariably involves considerable losses in output because it necessitates an interruption in the opertion of the machine as well as segregation of all such cigarettes or filler rod sections which are produced subsequent to tearing and prior to completion of a splicing operation.
Another serious drawback of unsatisfactory acceleration or deceleration of cigarette rod making or like machines is that the changes in speed often affect the operation of one or more consuming machines which are normally coupled with a cigarette rod making machine to form therewith a complete production line. For example, it is customary to directly couple a cigarette rod making machine with a filter cigarette making machine or with one or more packing machines. Certain units of consuming machines are highly sensitive to changes in speed. Such units include those which are employed to supply adhesive-coated uniting bands, to supply adhesive paste, to supply blanks for envelopes which are to be converted into packs for groups of plain or filter cigarettes, to supply filter rod sections of unit length or multiple unit length, and others. It was also found that abrupt changes in the speed of a producing machine or in the speed of a consuming machine which is directly coupled with the producing machine are likely to affect the quality of products, for example, by causing slip-page of rod-shaped articles during rolling which is resorted to for wrapping of such articles in adhesive-coating uniting bands (such rolling is the customary way of convoluting adhesive-coated uniting bands around groups of coaxial plain cigarettes and filter rod sections to convert such groups into filter cigarettes of unit length or multiple unit length). Even minor slippage can result in misalignment of articles, for exmple, by preventing the articles from entering flutes or equivalent receiving means in drums or analogous conveyors serving to transport the rolled articles past one or more testing, inverting, arraying, ejecting and/or other stations.
Even though it is desirable to operate a cigarette rod making machine, a filter rod making machine, a filter cigarette making machine or an analogous machine at a maximum speed, the operating speed of such machines must be temporarily reduced at relatively frequent intervals, for example, to insure satisfactory splicing of an expiring web of cigarette paper to a fresh web, to replenish the supply of paste in certain types of pasters, and/or for other purposes. Also, the operation of a high-speed cigarette rod making or like machine can be properly inspected and altered only when the machine is not running at full speed. Furthermore, it is often necessary to reduce the operating speed of one or more producing machines in response to stoppage or deceleration of directly coupled consuming machines. This is desirable in order to avoid complete stoppage of the producing machine or machines because the likelihood of producing defective articles prior to complete stoppage or during acceleration from zero speed is much more pronounced than during acceleration from a lower speed to a higher speed or during deceleration to a lower speed. It is further desirable to change the operating speed of producing machines in a production line as a function of the requirements of consuming machines, for example, as a function of fluctuations in the supply of rod-shaped articles in the magazine of a packing machine for plain or filter cigarettes, plain or filter-tipped cigars, cigarillos or like products.